Hey Michael,
Im working on a fairly large model for a real time engine, I use MoI for the modelling
(I miss instances or components like Sketchup and groups, but its OK, MoI workflow is so smooth I forget them hehe)
I try to avoid Overlapping faces, because the scene must be the lowest poly ammount possible

Firs I model with solids to be able to do booleans, I don't care about polycount at this stage
Then I remove all un-necessary faces (its an old industrial factory, reconverted as a modern office, we will never see the exterior anyway, so I remove all exterior faces by hand)
I also remove all the stuff that we don't gonna see...

The model is well optimized currently, but I would like to check if I don't missed overlapping faces (that can cause z-fighting)

Is it possible to have a script that select all surfaces that overlap themselves ? Even if they only overlap by 1%

For example two planar rectangles of 10cm by 1cm, sharing 1cm square

It would be usefull :)